1. Field of the Invention
The invention relates to an insulated electrical cable splice employing a particular dielectric fluid to encapsulate and insulate the splice. The dielectric fluid composition, having a specific gravity of at least 1.02, consists essentially of a silicone fluid and an additive, soluble in said silicone fluid, selected from the group consisting of trimethylsilyl treated (CH.sub.3).sub.3 SiO.sub.1/2 /SiO.sub.2 resin copolymer, dipropyleneglycoldibenzoate, dixylylethane, phenylxylylethane, and a mixture of [(CH.sub.3).sub.3 Si].sub.2 O treated silica and a silica aerogel. The invention also relates to employing the above dielectric fluid composition to fill an electrical cable's conductor interstices.
2. Description of the Prior Art
Electrical cable splices have been filled with greases, epoxies, and urethanes for the purpose of insulation. Little concern was placed on environmental factors, damage by water entry, and re-entry for maintenance and repair.
U.S. application Ser. No. 261,070, filed May 6, 1981, also assigned to Dow Corning Corporation, discloses the use of a silicone fluid with a specific gravity of at least 1.02 to insulate electrical cable splices. Though this fluid is better environmentally, and reduces the amount of damage by water entry, as compared to the greases, epoxies, and urethanes, it is costly.
It is thus an object of this invention to improve the cable splice by employing a particular dielectric fluid, having a specific gravity of at least 1.02, for the purpose of insulation. This particular dielectric fluid consists essentially of a silicone fluid and an additive, soluble in said silicone fluid, selected from the group consisting of trimethylsilyl treated (CH.sub.3).sub.3 SiO.sub.1/2 /SiO.sub.2 resin copolymer, dipropyleneglycoldibenzoate, dixylylethane, phenylxylylethane, and a mixture of [(CH.sub.3).sub.3 Si].sub.2 O treated silica and a silica aerogel. This dielectric fluid composition should cause the water to rise to the top of the container and prevent damage to the electrical cable splices. Another object of this invention is to provide a dielectric fluid composition in which the splice can be easily removed for maintenance or repair. Further objects of this invention include providing a cost-effective dielectric fluid composition that is environmentally safe, has low toxicity, and is able to withstand extreme temperatures.
Insulated electrical cables, such as those insulated with polyethylene, and cross-linked polyethylene, lose significant dielectric strength due to the formation of electrochemical trees in the insulation which may lead to premature failure of these cables. These tree-like patterns can be caused by sulfide or water attack on the insulation of the cables. The trees nucleate and grow only in the presence of conductive liquid. It is an object of this invention to provide a high dielectric strength, low dissipation factor, cost-effective dielectric fluid composition, having a specific gravity of at least 1.02, to fill the conductor interstices of an insulated electrical cable, such as those insulated with polyethylene or cross-linked polyethylene, to prevent electrochemical treeing. The dielectric fluid composition consists essentially of a silicone fluid and an additive, soluble in said silicone fluid, selected from the group consisting of trimethylsilyl treated (CH.sub.3).sub.3 SiO.sub.1/2 /SiO.sub.2 resin copolymer, dipropyleneglycoldibenzoate, dixylylethane, phenylxylylethane, and a mixture of [(CH.sub.3).sub.3 Si].sub.2 O treated silica and a silica aerogel.